This space race ....

[Ballzanya]

I was going to make a new thread to ask about this...you just saved me the trouble.

I don't know if there's been a real, technical discussion of the predalien here.  Maybe there has, and I'm covering old ground, but that's a risk I'm willing to take.

My primary concern with "Chet" is its abominable (yet undeniably efficient) reproductive mechanism.  Where the hell did it come from?  The Strauss bros imply in the DVD special features, and perhaps elsewhere, that Chet is a young queen, and that this ability is common to all young queens, who would need to start a hive quickly.  I can't deny the logic in that, but I still don't care for it.  (Yes, I know, I'm not arguing from evidence here.  Sue me.)  I also prefer to assume that the queen remains genetically pure and does not take on host characteristics.  Yet, if you look closely at the back of the predalien's head, it does have sort of queenlike features - the bifurcation down the middle, the smooth plates.  I'm too tired and lazy to grab a screenshot right now.

As usual, I've come up with a list of hypotheses.

1.  The predalien is a queen, and they can do that.  They also take host characteristics.
This is the default position, I guess; it's the position the directors have assumed.  However, their word is not law, as we've seen many times before.

2.  The predalien is a drone, but it's somehow mutated, perhaps due to something in the nature of the host.  Out-of-control acquisition of host characteristics might lead to things like the pigmentation, the mandibles, and the dreadlocks, but unless I start invoking unforeseen side effects, it doesn't really explain the reproductive method.

3.  The predalien is a queen, and normally they can't do that and/or don't take on host characteristics, but this time is an exception, again perhaps due somehow to the host.  This would explain the back of the predalien's head, and the fact that it can reproduce at all, but still doesn't explain why it can vomit babies out of its mouth.  We also don't know why using a Predator as a host would make any difference.

Now, in two of those hypotheses I've invoked Predators-as-hosts as an explanation.  I've seen this around before; the "dominant-Predator-DNA hypothesis" - it's not popular.  It's also not where I'm going.  I have a few sub-hypotheses here as well.

1.  Predators and aliens share an evolutionary heritage.  Perhaps they evolved on the same world, or perhaps aliens were created from Predator DNA (as something fierce to hunt, or by the Jockeys as a weapon to exterminate them).  Either way, due to some genetic "like-dissolves-like" principle, aliens born of Predators are bigger, meaner, and have the ability to exploit a reproductive mechanism not available to aliens bred from other hosts.  If this is the case, however, it begs the question: what's the point of having a queen and eggs?

2.  Predators have an extremely unusual biology.  Going in the complete opposite direction here, maybe most life in the Milky Way shares common biochemical characteristics (blame panspermia, blame the Jockeys, blame the conditions of the Predator homeworld, I don't know).  The aliens either evolved or were designed to take advantage of those similarities, and Predator DNA thows them for a loop.  All sorts of wacky gene-activation errors occur; more host DNA that necessary is integrated into the chestburster; queen genes are active when they should be silent; HOX genes get messed up so ovaries wind up in the throat, et cetera.

3.  Doping.  We're (I'm) pretty sure that the Predators did something to the aliens at Bouvetoya; they breed too quickly.  Maybe they used hormones or genetic material from their own body.  Alternately, maybe they (particularly Scar) use hormones derived from alien biology as a sort of steroid or athletic enhancer (remember Xeno-Zip and Royal Jelly from the comics and novels?)  Somehow, the presence of Predator biochemistry in the aliens or alien biochemistry in the Predator, combined with an alien in a Predator host, led to the sort of errors described in the hypothesis above.

Whew!  Sorry that was so long.  This is what I think about at midnight on a Monday night...

My take on the predalien is mostly no. 3.

At least in terms of the reproductive method. I would argue that all young queens CANNOT reproduce via this method. There is no natural phase a queen goes through from chestburster to adult queen that results in any reproduction, much less any type that would be half as efficient as egg laying.

I would say that this ability is a fluke and a mutation.  Something went wrong in the acquiring of host dna..etc. and an alien that would have been a normal queen became a freak of nature. With only partial queen dna and an excess of host dna.

It is clear and has been stated, that the predators did indeed interfere with the reproductive cycle of the aliens in order to speed up their gestation for the purposes of hunting them. They could have done something to inhibit the birth of a queen, thus ensuring that in the event that a hunt goes wrong, and the aliens run amok, no new queen will be born from it and they can just send an expert predator(s) to clean up the alien warriors or predaliens.etc

But clearly all the queen dna was not supressed and combined with the excess of predator dna, which may be because much of the predator's physiology proved adaptable and useful to the alien, much more so than the genes it could acquire from a human or a dog and so on, the result is the hideous mutant predalien with an almost inexplicable way to implant enhanced chestburster embyros into a host.

My guess is that it was born without the ability to make an egg laying tube, but yet possessed the hormones and the internal reproductive structures to produce the eggs which would normally be contained within an embryonic  facehugger which in turn would be housed in the rudamentary egg contained within the queen which would normally pass through the egg laying tube and complete its formation and eventually be laid.

To try and explain why the fuck the predalien could regurgitate it, I would guess that its just the jumbled mix of dna at work once again, making its partially queen, partially predalien internal structure a complete mess. With connections from the digestive system to partially formed, abnormal internal reproductive organs, the predalien's proto-eggs must be regurgitated due to it not having the reproductive pathways to the egg laying tube nor the genes to even grow the tube.

I personally hate the reproductive method as portrayed by the predalien in AVP-R but if Thedus ever puts something up about it on the anchorpoint essays, This is my possible contribution for consideration.

[WrathRaptor]

After reading through some of this, I would have to agree with several points made about the Xenomorph's genetic code.  It is obvious to me that the alien should have a basic code that is incorporated all the time, no matter the host involved.  If the alien's genome changed as frequently with every type of host it would break down and you would find that in a short period of time that the alien, as we know it, would cease to exist and would be replaced with numerous organisms of a distantly related nature. 

In incorporating host DNA I would propose that there aren't necessarily "gaps" in the DNA but more likely associated enzymatic pathways that incorporate host DNA into the alien DNA.  Much in a similar fashion as some viruses incorporate their DNA into their host's genome in the real world today.  This is a desirable attribute in a bio-weapon as it is thought the aliens represent.  The scenario would be as follows, on a genetic level, that is:

Host is implanted.

Embryo develops 

As embryo develops specific proteins associated with the replication of the xenomorph DNA seek out and bind to portions of the host DNA.  Once "tagged", another alien protein binds and cuts the host DNA from its own genome.  A transport protein is then employed to move the host DNA fragment to a specific site on an alien chromosome that is used for incorporating foreign DNA.  Another protein comes in and binds the host DNA to the alien chromosome.  Then the alien-host chromosome undergoes replication thereby permanently incorporating host DNA into every cell of the xenomorph.

Embryo matures into chestburster

Chestburster emerges with "typical" ontogenetic appearance of the xenomorph with characteristics of the host incorporated in the form of structures that appear in early stages of embryonic development of the host (i.e. the mandibles of the predator in the predalien chestburster but dreadlocks not yet apparent).

Chestburster matures into a full grown xenomorph and as it undergoes its molting process more advanced features of the host are incorporated into the overall body plan.

Also, I would suggest that when A Queen has arisen within a hive and is laying eggs or implanting embryos like the Predalien that the gametes used in developing those embryos contain only the original xenomorph DNA within them in order to maintain continuity of the species.  Therefore gametes form in embryos prior to any stage where the host DNA is incorporated into the alien genome, and then those portions of the alien genome responsible for host DNA incorporation are deactivated within the gametes before the incorporation process begins in the rest of the embryo.  Thus, preserving the original alien genome.

For the xenomorphs this has proven to be an exceptional survival strategy.  In the above process the xenomorph can insure that it is incorporating DNA from its hosts into its own genome.  In doing so it is likely that the xenomorph will attain genes that will increase its survival in what amounts to an alien environment with respect to itself.  This process of incorporation of foreign genes could very well result in the aliens being able to attain genes that permit them to operate in an oxygen atmosphere, an atmosphere that is nominally corrosive and toxic and results in the formation of free radicals in all organisms on this planet that come into contact with oxygen.  This is just an example of a benefit that could be reaped by the incorporation process.

I could go into extravagant detail as to the biomolecular and chemical nature of such a process, but I leave that open for later if anyone is interested in discussing such a proposal.

[Hieronymus]

I could go into extravagant detail as to the biomolecular and chemical nature of such a process, but I leave that open for later if anyone is interested in discussing such a proposal.

Yes, YES!  I take it that's your specialty in the real world?  Or just a hobby?

This process of incorporation of foreign genes could very well result in the aliens being able to attain genes that permit them to operate in an oxygen atmosphere, an atmosphere that is nominally corrosive and toxic and results in the formation of free radicals in all organisms on this planet that come into contact with oxygen.

I'm afraid I have to differ with you there.  The alien biochemistry is so totally foreign that it's unlikely that the host adaptations of a biochemical nature could be incorporated into their own.  For instance, you bring up oxygen, but there's probably no way the Krebs cycle could take place in an alien's body, which would preclude them from copying our own adaptations to oxygen.  And Christ knows the alien blood is more oxidative than probably anything we know of (if it is in fact an acid and not some other kind of corrosive fluid).

I figure the adaptations are mostly anatomical, and assist the alien in moving around the environment to which the hosts were adapted - as well as hunting the hosts themselves.  For instance, you'd want something with thick, sturdy limbs in a high-gravity environment, and something with long, graceful limbs in a low-gravity environment.

As embryo develops specific proteins associated with the replication of the xenomorph DNA seek out and bind to portions of the host DNA.  Once "tagged", another alien protein binds and cuts the host DNA from its own genome.  A transport protein is then employed to move the host DNA fragment to a specific site on an alien chromosome that is used for incorporating foreign DNA.  Another protein comes in and binds the host DNA to the alien chromosome.  Then the alien-host chromosome undergoes replication thereby permanently incorporating host DNA into every cell of the xenomorph.
...
Chestburster emerges with "typical" ontogenetic appearance of the xenomorph with characteristics of the host incorporated in the form of structures that appear in early stages of embryonic development of the host (i.e. the mandibles of the predator in the predalien chestburster but dreadlocks not yet apparent).

This is only marginally related, but you got me to thinking about something else.  How does the alien "know" which host DNA segments to select?

If my suspicions are correct that the alien only takes anatomical traits, then it probably only takes genes which are only active during embryological development.  But again, how does it know to look for them?

Maybe the alien has a way to "reset" certain host cells to a totipotent state.  We're trying to do the same thing now to create stem cells and clones and stuff, but the process is complicated.  Maybe the alien has found something simpler (and more importantly, universal); a sort of molecular reset switch.  It would then only need to capture the mRNA being produced the most...

[deezelboy]

This is only marginally related, but you got me to thinking about something else.  How does the alien "know" which host DNA segments to select?

Slightly more tangential, but how does the Alien 'know' what the genes are going to do in the first place?  It's not in any way intuitive.

I could go into extravagant detail as to the biomolecular and chemical nature of such a process, but I leave that open for later if anyone is interested in discussing such a proposal.

I'm with Hieronymus on this one.  Go for it!

[Thedus]

I could go into extravagant detail as to the biomolecular and chemical nature of such a process, but I leave that open for later if anyone is interested in discussing such a proposal.

I third the motion of "Please Do."

....And being that an admin and a moderator have put in their vote to have you go into extravagant detail I think you are pretty much bound by law to do so.

[The Companyman]

I to would like to hear it...

And when the Company makes a request, it's like E.F. Hutton.

EDIT: In a friendly way!

[WrathRaptor]

Alright, I'll work it up into detail.

And now that I look back at what I said about oxygen and attaining abilities to survive in varying environments.  I have to concur with what's been said, probably not likely.  But the incorporation of genes that develop physical structures is more likely and poses an interesting problem as to how to identify them.

I'll have some fun with this.

And just to answer a question. . .Cell & Molecular biology is my field.

[Thedus]

And just to answer a question. . .Cell & Molecular biology is my field.

Excellent!  Welcome to AXP. 

[Miedvied]

I would like to take a step back and simply say that within the confines of real biology, the behavior of the aliens with respect to incorporation of host genetics is outright impossible. Any/all explanations are essentially handwaving, with varying levels of detail to obscure the fact. I think it would be fruitful, then, to consciously say "How we can we handwave?" rather than "How would the aliens accomplish this?"

Genetic incorporation as described would not work. Altering the final morphology requires altering the developmental biology; not just the genes, but when they're activated, for how long, in what sequence, in what cells, et al. For this functionality to be plug-and-play would require remarkable genetic homogeneity, which is more than can be asked for across multiple alien species. Yes, virii do this, but note that virii do not seek to change the final functional morphology of their hosts - they simply use the host's protein synthesis pathways to produce more of themselves before destroying the host cell.

"Static" genetics would not work either. Aliens, much like any other species, will have varying genetics over time - queens included. DNA replication and synthesis is of remarkably high fidelity; however, it is far from 100% error-proof. It quite literally *cannot* be, due to the ultimately stochastic nature of the chemical processes involved. The idea, then, that the queen is a genetic "reset" button can only be upheld with limitations: they may "reset" to their unique mold, rather than some ubiquitous "Alien" mold.

Frankly, there is no "real" process that can allow what we see. All genetic recombination is random; it is the action of random nuclear components in haphazard patterns.

I would put forth, then, the hypothesis as follows:

(1) Facehuggers inject an "egg." An egg is an already complete organism; one that has its full genetic complement as well as the resources to begin development. Let us argue, then, that this is not an egg but rather a number of eggs in the human fashion: a collection of individual cells, *each* of which is capable of maturation into an alien.

(2) The cells of this "egg" are competent to uptake exogenous DNA, and incorporate it. Random incorporation will result in the immediate death of the vast majority of these cells; a minority will develop into a non-viable organism. Let us handwave the statistics such that every 1-3 hosts will produce a viable alien.

(3) Competence is dependent on environmental quorum signaling. A number of bacteria alter their behavior depending on the concentration of signaling molecules from neighboring bacteria: staph infections mitigate their virulence depending on their concentration, such that at low concentrations they essentially "hide" and as such try to avoid the immune system until they can regenerate their numbers. We will assume the aliens are competent for DNA uptake when concentrations of ambient signaling molecules are low: at high numbers, the Aliens are presumably fit for their environment, and do not need to undertake the risks associated with genetic recombination. All but one of the egg cells apoptose; a host body cannot provide nutrients for more than one alien.

(4) As only the aliens whose genetic recombinations have not crippled them will survive, there will be a very real selection pressure to ensure that only neutral or advantageous genetic changes (as a net value) will survive in the aliens.

(5) These surviving Aliens bring their genetic samples back to the hive/Queen. The Queen has a genetic repository of neutral or postive-value genetic changes to incorporate into its offspring via this mechanism. Advantageous traits will tend to be brought back by multiple aliens; if multiple aliens all return with the same advantageous genetic trait, the queen can "know" that this trait is useful, and pass it onto future offspring. The number of survivors with a trait essentially act as "votes" to encourage the queen to pass that trait onto further Aliens.

I don't know if this is entirely consistent with the content of the films, but I think it's the closest one can come to a plausible biological justification of constant genetic upheaval and integration of host traits across multiple alien species.

[deezelboy]

I like this very much - it certainly explains how the Aliens know which genes to snatch through the trial-and-error mechanism.  Nice one!

[Thedus]

[Miracle Max] Woo hoo hoo - Look who knows so much! [/Miracle Max]

Nicely done (+).  And welcome.

[Hieronymus]

Not bad for handwaving.    Naturally, most of what we do here is handwaving - the alien has a lot of fantastic aspects that practically make it a necessity.  But it's always nice to be able to apply real-world knowledge to them.

The queen as genetic reservoir doesn't necessarily contradict anything in the films.  In fact, the homogeneity of the hives we've seen suggests something more than the trial-and-error approach of steps 1 through 4, so this is an intriguing possibility.

[Linguafoeda acheronsis]

"1: The xenomorphs as we see in the movies are in their more of less 'pure' form. No matter what hosts they take, they'd still look more or less the same. They only absorb a small amount of DNA from their hosts, so over generations they'd still look like the human/dog creatures we see in the first four films, with only a few small modifications such as how they move and slight changes in behavior."  - beckmen

This is the right one in my opinion.